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NSTX-U Initial Operations Plan 5 Year Plan for Scenarios and Control

NSTX-U. Supported by. NSTX-U Initial Operations Plan 5 Year Plan for Scenarios and Control. S.P. Gerhardt, PPPL E. Kolemen , PPPL for the NSTX-U Research Team. Coll of Wm & Mary Columbia U CompX General Atomics FIU INL Johns Hopkins U LANL LLNL Lodestar MIT Lehigh U

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NSTX-U Initial Operations Plan 5 Year Plan for Scenarios and Control

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  1. NSTX-U Supported by NSTX-U Initial Operations Plan 5 Year Plan for Scenarios and Control S.P. Gerhardt, PPPL E. Kolemen, PPPL for the NSTX-U Research Team Coll of Wm & Mary Columbia U CompX General Atomics FIU INL Johns Hopkins U LANL LLNL Lodestar MIT Lehigh U Nova Photonics ORNL PPPL Princeton U Purdue U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Illinois U Maryland U Rochester U Tennessee U Tulsa U Washington U Wisconsin X Science LLC Culham Sci Ctr York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAEA Inst for Nucl Res, Kiev Ioffe Inst TRINITI Chonbuk Natl U NFRI KAIST POSTECH Seoul Natl U ASIPP CIEMAT FOM Inst DIFFER ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep NSTX-U 5 Year Plan Review LSB B318, PPPL May 21-23, 2013

  2. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extension of the high-current, partial-inductive space to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control • Thrust 3: Automated Rampdowns • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  3. Operations Activities Designed to Fit in the Existing NSTX-U Project Schedule • Projected Near Term Schedule:

  4. Initial Operations Plans Designed to Rapidly Recover Physics Operations Capabilities • Plasma Operations with: • Ip≤1.0 MA, BT≤0.5 • Develop: • Breakdown and current ramp scenarios • Shape & position control • Reliable H-mode • Diagnostic operations Continue to add diagnostic & control capabilities while initiating physics experiments. ISTP: (Integrated Systems Test Procedure) Establishes facility in state of readiness for operations. Ip≤1.5-1.6 MA BT≤0.75-0.8 July-Sept. 2014 MPTS Calibrations, Bake Out, CD-4 Operations Commissioning Phys. Ops Phys. Ops ISTP-1 & CD-4 Prep ISTP-2 ~ 2-3 Months ISTP-2 Required to increase the field and current for later research phase Attempt 50 kA CD-4 plasma before bake-out. If water in PFCs prevents success, then repeat after bake-out.

  5. NSTX-U Field and Current Capabilities Will Be Increased Over a ~3 Year Period • 1st year goal: operating points with forces up to ½ the way between NSTX and NSTX-U, ½ the design-point heating of any coil • Will permit up to ~5 second operation at BT~0.65 • 2nd year goal: Full field and current, but still limiting the coil heating • Will revisit year 2 parameters once year 1 data has been accumulated • 3rd year goal: Full capability NSTX-Upgrade engineers developing a plan for mechanical diagnostics to assess the accuracy of the mechanical models underlying protection levels

  6. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extension of the high-current, partial-inductive space to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control • Thrust 3: Automated Rampdowns • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  7. ASC Research Targets Integrated, Steady-State Scenario Needs for FNSF/CTF and ITER Steady-state scenarios for ITER or a CTF/FNST must: • Have 100% non-inductive current drive. • NSTX-U ASC: Explore a range of bN with 100% non-inductive CD. • Control the divertor heat flux to be within acceptable material limits. • NSTX-U ASC: divertor geometry and radiation control. • Simultaneously optimize confinement and passive global stability. • NSTX-U ASC: optimization and control of the boundary, rotation and current profiles. • Detect and respond to disruptions and off-normal events. • NSTX-U ASC: disruption detection and soft-shutdowns. NSTX Operational Space: bN vs A >1tE average for each point Conventional NSTX Operating Space High-A Experiment During FY-11 Run

  8. ASC Research Targets Integrated, Steady-State Scenario Needs for FNSF/CTF and ITER Russia PPPL Steady-state scenarios for ITER or a CTF/FNST must: • Have 100% non-inductive current drive. • NSTX-U ASC: Explore a range of bN with 100% non-inductive CD. • Control the divertor heat flux to be within acceptable material limits. • NSTX-U ASC: divertor geometry and radiation control. • Simultaneously optimize confinement and passive global stability. • NSTX-U ASC: optimization and control of the boundary, rotation and current profiles. • Detect and respond to disruptions and off-normal events. • NSTX-U ASC: disruption detection and soft-shutdowns. ORNL UK

  9. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period ASC Programmatic Goal For 5 Year Plan: Develop the basis for integrated, steady-state operation and axisymmetric control for next-step STs, while helping resolve key scenario and control issues for ITER. ASC Operational Goal For 5 Year Plan: Establish stationary, 100% non-inductive operation, and partial inductive operation up to IP=2 MA, for 5 seconds over a wide range of Greenwald fractions. Research required to meet these goals divided into four thrusts.

  10. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extend the high-current, partial-inductive scenarios to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control. • Thrust 3: Disruption Avoidance By Controlled Discharge Shutdown • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF. Four thrusts support all 5 high-level programmatic goals for NSTX-U (see J. Menard talk)

  11. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extend the high-current, partial-inductive scenarios to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control. • Thrust 3: Disruption Avoidance By Controlled Discharge Shutdown • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  12. Anticipate The Non-Inductive Current Level at BT=1.0 T and Pinj=12.6 MW To Be Between ~900 & ~1300 kA Thrust #1 Dashed: ITER-98 confinement scaling Broad, H98=1 Broad, H98=1 Narrow, H98=1 Narrow, H98=1 Free-Boundary TRANSP Calculations S.P. Gerhardt, et al, Nuclear Fusion 52 083020 (2012) • Fix: 1.0T, Pinj=12.6 MW, fGW=0.72 • Fix: A=1.75, k=2.8 • Determine the non-inductive current level for 2 confinement and 2 profile assumptions…yields 4 different projections. Broad, H98=1 Narrow, H98=1

  13. Anticipate The Non-Inductive Current Level at BT=1.0 T and Pinj=12.6 MW To Be Between ~900 & ~1300 kA Thrust #1 Dashed: ITER-98 confinement scaling Solid: ST confinement scaling Narrow, HST=1 Narrow, HST=1 Broad, HST=1 Broad, HST=1 Broad, H98=1 Broad, H98=1 Narrow, H98=1 (S. Kaye, NF 2006) Narrow, H98=1 Free-Boundary TRANSP Calculations S.P. Gerhardt, et al, Nuclear Fusion 52 083020 (2012) • Fix: 1.0T, Pinj=12.6 MW, fGW=0.72 • Fix: A=1.75, k=2.8 • Determine the non-inductive current level for 2 confinement and 2 profile assumptions…yields 4 different projections. Broad, HST=1 Narrow, HST=1 Broad, H98=1 Narrow, H98=1

  14. Non-Inductive Operating Points Projected Over a Range of Toroidal Fields, Densities, and Confinement Levels Thrust #1 BT=1.0 T, IP=1 MA, Pinj=12.6 MW • TRANSP calculations yield research goals for 100% non-inductive sustainment. • Related research: non-inductive ramp-up: • Reduce IP beneath the 100% non-inductive operating point, assess non-inductive overdrive. • See SFSU talk by R. Raman for details. • Goal for end of 5YP: demonstrate non-inductive formation, ramp-up, and sustainment in a single discharge. Contours of Non-Inductive Fraction fNI=1 Contours of qmin qmin=1 Particle & heat flux control, NBCD tools required to realize these scenarios discussed in upcoming slides.

  15. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extend the high-current, partial-inductive scenarios to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control. • Thrust 3: Disruption Avoidance By Controlled Discharge Shutdown • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  16. Optimizing the Early Discharge Evolution Will Play an Important Role in Achieving Low Collisionality at High-Current Frequency Drops to Zero 132847: Fueled from low-field side BP, MS TSGs

  17. Optimizing the Early Discharge Evolution Will Play an Important Role in Achieving Low Collisionality at High-Current • Timing and magnitude of fueling has profound impact on discharge evolution, will be optimized in NSTX-U. • Will slower IP ramps w/ larger solenoid facilitate reduced fueling? • Will improved solenoid design and reduced error fields improve lower-density startup? • Will the extra torque from the new beams reduce prevalence of locking? Frequency Saturates 132847: Fueled from low-field side 132850: Fueled from both low- and high- field sides Milestone R14-1 BP, MS TSGs

  18. Will Develop Long-Pulse Partial Inductive Operation Up to 2 MA with High Power Thrust #1 • Two motivations for partial inductive operation: • High-IP operation supports collisionality scaling and divertor heat flux studies • Long pulse operation for particle retention and disruptivity reduction studies • Years 1 & 2 of ops. (2015 & 2016): Re-optimize startup for reduced fueling and low collisionality. • Optimize fueling, ramp-rate, error field correction, torque input to facilitate reduced density • Years 3 & 4 of ops. (2017-2018): Performance Extension • Discharges up to 2 MA for 5 seconds. • Long pulse at ~1 MA for up to 10 seconds • Assess HHFW for increased power and profile variations. • High-IP & long pulse development will be connected to progress in: • Particle Control • Heat flux mitigation BT=0.75 T, 8-10 Second Discharge Scenarios Limited by qmin>1.1 or OH Coil I2t 2 Confinement and 2 Profile Assumptions 6x65 kV Beams Longest Ever NSTX Discharge 3 x Modulated 80 kV Beams Addresses milestone R15-3, Supports milestone R15-1 BP, MS TSGs

  19. Operation Tools for Density & Impurity Control Thrust #1 Years 1 & 2 of ops. (2015-2016): Examine Wall Conditioning, Fueling, and ELM Pacing Boronized PFC Studies • Utilize regimes with natural ELMs to control impurity accumulation • Between-shot He glow for wall conditioning • Deuterium inventory may rise throughout the discharge • Lithiated PFC Studies • High-tE, ELM-free regimes w/ Li conditioning • Pulsed 3D fields or lithium granules for ELM pacing to provide impurity control • Deuterium inventory likely well controlled, but unclear if target Zeff~2 can be achieved Techniques to Be Covered in Greater Detail in Talks By Maingi, Soukhanovskii, Jaworski BP, M&P TSGs

  20. Operation Tools for Density & Impurity Control Thrust #1 Years 1 & 2 of ops. (2015-2016): Examine Wall Conditioning, Fueling, and ELM Pacing Boronized PFC Studies • Utilize regimes with natural ELMs to control impurity accumulation • Between-shot He glow for wall conditioning • Deuterium inventory may rise throughout the discharge • Lithiated PFC Studies • High-tE, ELM-free regimes w/ Li conditioning • Pulsed 3D fields or lithium granules for ELM pacing to provide impurity control • Deuterium inventory likely well controlled, but unclear if target Zeff~2 can be achieved Realtime Density Measurements via FIReTIP PCS control of Supersonic Gas Inj. for Density Control Both Scenarios: Techniques to Be Covered in Greater Detail in Talks By Maingi, Soukhanovskii, Jaworski BP, M&P TSGs

  21. Operation Tools for Density & Impurity Control Thrust #1 Years 1 & 2 of ops. (2015-2016): Examine Wall Conditioning, Fueling, and ELM Pacing Boronized PFC Studies • Utilize regimes with natural ELMs to control impurity accumulation • Between-shot He glow for wall conditioning • Deuterium inventory may rise throughout the discharge • Lithiated PFC Studies • High-tE, ELM-free regimes w/ Li conditioning • Pulsed 3D fields or lithium granules for ELM pacing to provide impurity control • Deuterium inventory likely well controlled, but unclear if target Zeff~2 can be achieved Realtime Density Measurements via FIReTIP PCS control of Supersonic Gas Inj. for Density Control Both Scenarios: Years 3 & 4 of ops. (2017-2018): Utilize Cryo-pumping and Partial NCC • Cryo-pump in lower-divertor to provide deuterium inventory control • Natural or paced ELMs to control core impurity accumulation • Make comparisons to regimes with paced ELMs and lithium pumping • Partial NCC to aid in ELM pacing and RMP studies • Attempt direct modification of pedestal particle transport via RMP • Determine optimal spectrum for magnetic ELM pacing, with minimal rotation damping Techniques to Be Covered in Greater Detail in Talks By Maingi, Soukhanovskii, Jaworski BP, M&P TSGs

  22. Full Utilization of the NSTX-U Will Require Heat Flux Mitigation Solutions • Limit #1: Thermal stresses in target tiles can exceed ATJ graphite limits. • Inner horizontal target tiles qualified for 5 sec operation at Qave=5 MW/m2, QPk=8.0 MW/m2 • Limit #2: Desire to avoid tile surface temperatures exceeding Tmax~1200 C. • Due to enhanced sublimation. • Conservative assumption: • Primary solutions: 100% NI Long Pulse Highest Power BP TSG

  23. Full Utilization of the NSTX-U Will Require Heat Flux Mitigation Solutions • Limit #1: Thermal stresses in target tiles can exceed ATJ graphite limits. • Inner horizontal target tiles qualified for 5 sec operation at Qave=5 MW/m2, QPk=8.0 MW/m2 • Limit #2: Desire to avoid tile surface temperatures exceeding Tmax~1200 C. • Due to enhanced sublimation. • Conservative assumption: • Primary solutions: Broadening the heat channel (fexp) via the snowflake divertor Increasing the fraction of radiated power (decreasing fdiv) 100% NI Long Pulse Highest Power BP TSG

  24. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extend the high-current, partial-inductive scenarios to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control. • Thrust 3: Disruption Avoidance By Controlled Discharge Shutdown • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  25. Snowflake Geometry and/or Divertor Radiation Control Required for High-Current Operation Thrust #2 Snowflake Divertor in NSTX-U Increases divertor volume and flux expansion. • Physics of these techniques to be covered in Boundary Physics talk • Control development plans • Pre-operational year (2014): • Collaborate on snowflake divertor physics and control experiments at DIII-D • Years 1 & 2 of ops (2015-2016): • Develop schemes for snowflake divertor control (dual X-point control) using new divertor coils • Assess magnetic balance control in the presence of 4 X-points • Develop the realtime measurements for divertor radiation control • Assess impact on core physics performance • Between years 2 & 3 of ops: Install cryo-pump • Years 3 & 4 of ops (2017-2018): • Utilize cryo-pump + snowflake divertor for increasing the pulse length at higher current • Begin implementation of closed loop radiative divertor control • Assess impact of divertor/edge impurities on the core scenario Milestone R14-3 BP TSG

  26. NSTX-U Will Have Significant Actuators For Profile Control Studies Thrust #2 Rotation Profile Actuators Torque Profiles From 6 Different NB Sources Largest Rtan Neutral Beams (TRANSP) Smallest Rtan Measured and Calculated Torque Profiles from 3D Fields (n=3) Zhu, et al., PRL MS, EP TSGs

  27. NSTX-U Will Have Significant Actuators For Profile Control Studies Thrust #2 Rotation Profile Actuators q-Profile Actuators Torque Profiles From 6 Different NB Sources Variations in Beam Sources 800 kA Partial Inductive, 87% < fNI < 100% Largest Rtan 800 kA and 1 T [50,60,70,130] cm [50,60,120,130] cm [60,70,110,120] cm [70,110,120,130] cm Neutral Beams (TRANSP) Smallest Rtan Measured and Calculated Torque Profiles from 3D Fields Variations in Outer Gap (1.69<A<1.81) (n=3) 27 22 17 12 7 2 Milestone R14-3 Zhu, et al., PRL Outer Gap MS, EP TSGs

  28. Profile Control Techniques Will be Developed To Support NSTX-U Physics Studies and Next-Step ST Designs Thrust #2 • Pre-ops. Year: Continue developing control schemes for NSTX-U actuators. • Lehigh: Collaboration on q-profile control algorithms, building on their experience at DIII-D. • Princeton University: Collaboration on rotation profile control algorithms. • Continue operations collaborations on KSTAR and EAST. • Years 1 & 2 of ops. (2014-2015): • Test ability of different NB source selection to change the q-profile. • Study as a function of density, fast-ion b, source voltage. • Assess the NBCD calculations underpinning NSTX-U and most next-step ST studies. • Commission real-time MSE (Nova Photonics) and rotation (PPPL) diagnostics. • Make first tests of bN + central rotation (FT,0) and, if feasible, bN+qmin control. • Years 3 & 4 of ops. (2016-2017): • Expand rotation control to the full profile. • Complete bN+qmin control and assess combined control, e.g., bN+FT,0+qmin. • Assess NTV capabilities from NCC for enhanced rotation profile control. • Work with MS group to develop physics-based requests for disruption avoidance goals. Milestone R14-3 MS, EP TSGs

  29. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extend the high-current, partial-inductive scenarios to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control. • Thrust 3: Disruption Avoidance By Controlled Discharge Shutdown • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  30. Disruption Avoidance Via Discharge Shut-Down Will be Developed Thrust #3 • Disruption detection algorithms have been developed using NSTX data • Compare diagnostic data to thresholds & assign “penalty points” when thresholds are exceeded. • Sum the “penalty point”, and declare a warning when the point total exceeds a given threshold. • Provides the foundation of disruption detection in NSTX-U. • Years 1 & 2 of ops.: • Implement basic detector in PCS, and design architecture of control response. • Assess accuracy of predictor for NSTX-U disruptions, and refine as necessary. • Do initial tests of automated rampdowns. • Years 3 & 4 of ops.: • Add additional realtime diagnostics for improved detection fidelity. • Optimize rampdowns for different types of alarms. • Incorporate on-line MGI if it appears promising. Under consideration for an ITPA joint experiment. (S.P. Gerhardt, et al., accepted for publication in Nuclear Fusion) • Connections of MS TSG: • n>=1 control, including disruption avoidance scenarios, covered by MS TSG. • MGI physics covered by MS TSG Milestone R13-4 MS TSG

  31. Outline • Plans for Entering the First NSTX-U Operations Period • ASC Research Plans for 5-year Period • Thrust 1: Scenario Physics • Development of 100% non-inductive operation. • Extend the high-current, partial-inductive scenarios to long-pulse. • Thrust 2: Axisymmetric Control Development • Develop methods to control the heat flux for high-power scenarios. • Develop rotation and current profile control. • Thrust 3: Disruption Avoidance By Controlled Discharge Shutdown • Develop detection of impending disruptions. • Develop techniques for the automated termination of discharges. • Thrust 4: Scenario Physics for Next Step Devices • Determine the optimal, simultaneous q- and rotation profiles. • Study the conditions for classical beam current drive. • Explore & validate integrated models for projections to FNSF.

  32. Explore Optimal Scenarios for Next Step STsAll Topics in Collaboration with Other TSGs Thrust #4 Fast Ion Diffusivity 1 T, 1 MA 12.6 MW 0 m2/s 1 m2/s • Study optimal current and rotation profiles for confinement and stability. • e.g., what value of qmin provides the best core confinement and stability? • Explore alternative optimal scenarios, such as EPH or w/ ITBs. • Study the conditions for classical beam current drive • Study what parameters determine when *AE modes lead to anomalies in the fast ion diffusion and NBCD. • Can anomalous diffusion be used for scenario optimization? • Assess integrated models for projections to FNSF. • Compare NBCD & q-profile predictions from integrated codes to NSTX-U. • Project scenarios to ST FNSF devices. qmin qmin Pressure Peaking Pressure Peaking H98(y,2) H98(y,2) H98(y,2) atan(dWwith-wall/5) atan(dWwith-wall/5) fGreenwald fGreenwald Red: Internal Modes Unstable Green: stable Blue/Black: External modes unstable Milestone R15-2 MS, EP, T&T TSGs

  33. ASC Research Supports Development of High-Performance Integrated Scenarios for NSTX-U, FNSF & ITER • Plans for initial NSTX-U operations have been formed, in support of physics program objectives • ASC 5-year plan designed to provide solutions for • the operations needs for the NSTX-U research program, and • scenarios for next-step ST scenarios • while providing important scenario and control support for ITER. • Research will address outstanding needs by • developing stationary scenarios over a range of non-inductive fractions, plasma currents, and collisionalities • developing measurements, algorithms, and actuators for control of • the current & rotation profiles, • the core density, • the divertor geometry and radiation, • validating models for NBCD & thermal transport to enable projections for next-step STs

  34. Backup

  35. Trade-Off Between Power and Pulse Length For the NSTX (TFTR) Neutral Beams • Pulse duration at a given power limited by heating on the primary energy ion dump. • Designs exist to increase the size of the ion dumps, increase the allowed pulse duration.

  36. Criterion For Heat Flux Limits • Calibrate expression for tile surface temperature against engineering models: • Tsurf=CQavet1/2 • Use Tsurf=1000 C, t=5 s, Qavg=5 MW/m2. • Derive C~90 Cm2/MWs1/2 • Derive heat flux Q from simple scalings:

  37. Physics and Engineering Operations Activities Over the Next ~Year Will Provide the Baseline For NSTX-U Operations • Upgrading the Plasma Control System (PCS) for NSTX-U. • Upgrading to new 32-core computer. • Switching to 64 bit real-time Linux with advanced debugging tools. • Upgrading shape-control codes for new divertor coils, gas injector controls for new/additional injectors, additional physics algorithms • Improving the real-time data-stream. • Assisting with development of a new Digital Coil Protection System (DCPS). • Upgrading HHFW antenna feedthroughs for higher disruption forces. • Boundary Physics Operations • Improving the PFC geometry in the vicinity of the CHI gap to protect the vessel and coils. • Developing an upgraded Boronization system. • Developing lithium technologies (granule injector, upward LITER). • Diagnostic Upgrades • Fabricating new port covers to support high-priority diagnostics. • Installing additional, redundant magnetic sensors. • Upgrading diagnostics: Bolometry (PPPL), ssNPAs, spectroscopy (collaborators) • Physics & Engineering Operations • Replacing electronics that control & protect rectifiers. • Upgrading the poloidal field coil supplies to support up-down symmetric snowflake divertors. • Developing PF null/breakdown scenario w/ new CS.

  38. Pursue 100% Non-Inductive Current at Progressively Higher IP and BT Thrust #1 TRANSP Projections for 100% Non-Inductive Scenarios Each polygon for a given engineering configuration, multiple profile and confinement assumptions • Free-Boundary TRANSP calculations of NSTX-U operations points. • See: S.P. Gerhardt, et al, Nuclear Fusion 52 083020 (2013) Projected Non-Inductive Current Levels for k~2.85, A~1.75, fGW=0.7 NSTX Data NSTX Data NSTX Data NSTX Data End of year 1 target BP, MS TSGs

  39. Shape/Position & Fueling Control Will Be Developed to Support NSTX-U Operations Thrust #2 • Fueling Control Considerations • Realization of lowest-collisionality will require high-efficiency fueling. • Full utilization of the cryo-pump will require better control of fueling • Years 1 & 2 of ops. • Utilize super-sonic gas injection for improved fueling during the current ramp. • Develop realtime density measurements. • Assess closed-loop density control during the current ramp. • Years 3 & 4 of ops. • Utilize cryo-pumping + advanced fueling to achieve closed-loop density control during the discharge flat-top. • Shape/Position Control Considerations • Vertical control of high-A NSTX plasmas found to be problematic when li exceeded ~0.6. • Boundary and PMI research programs will require accurate control of the strikepoints. • Years 1 & 2 of ops. • Assess vertical stability of NSTX-U plasmas. • Improve control as necessary via better algorithms or measurements. • Re-tune strike-point controllers for new divertor coils. • Years 3 & 4 of ops. • Implement realtime n=0 stability and loss of control assessments. • Connection to Thrust #3. BP TSG

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